Lung cancer is a major cause of cancer-related mortality in the world with the primary cause of death being from tumor metastases. Due to the inability to control local tumor spread as well as failure to treat metastatic tumors at distant sites, patients often relapse resulting in resistance to treatment. Therefore, novel forms of treatment modalities are mandated. One therapeutic approach that has shown recent promise is gene therapy. Although adenovirus-mediated gene transfer for treatment of cancer has shown clinical promise, its use has been limited to loco-regional treatment owing to toxicity and immune response. An alternate treatment strategy we envision is the systemic delivery of novel tumor suppressor genes encapsulated in a non-viral vector that not only are less immunogenic but can effectively deliver therapeutic genes to both primary and metastatic tumor. Preclinical studies from our laboratory and others have demonstrated DOTAP:Cholesterol (DOTAP:Chol) liposome to be an efficient vector for systemic delivery of therapeutic genes to primary and experimental metastatic tumors in animals, resulting in tumor suppression and prolonged animal survival. Based on our preclinical studies we have initiated the first systemic Phase I cancer gene therapy clinical trial for advanced chemotherapy refractory non-small cell lung cancer where a tumor suppressor gene (Fus1) encapsulated in DOTAP:Chol. liposome (lipoplex) is administered systemically. We, in the present proposal, plan to conduct additional preclinical studies and obtain new information to advance our understanding on the role of vector-mediated inflammatory response;develop methods to circumvent the host-response;and study the effects of small molecule inhibitors on therapeutic efficacy and on suppressing vector-mediated inflammatory response. For this purpose we have identified three specific aims: Aim 1: Study the lipoplex-mediated inflammatory response in tumor-bearing and non tumor-bearing mice. Aim 2: Establish the mechanism of induction of inflammatory response by lipoplex. Aim 3: Develop strategies to overcome the lipoplex-mediated inflammatory response and measure the therapeutic efficacy in vivo. The goals of the specific aims proposed in this application will be achieved by utilizing molecular, cellular and animal models. The research findings generated from the proposed studies will be important for clinical translation and will have immediate application in the clinic for the present trial and in the design of future clinical trials. PUBLIC HEALTH RELEVANCE: The major goal of the proposal is to develop an efficient systemic non-viral gene delivery system for treatment of lung cancer. In the present proposal we plan to study the molecular mechanism of inflammatory response as well as develop strategies to overcome the vector-induced inflammatory response using in vitro and in vivo models. Our studies will lead to an improved systemic gene delivery vehicle for lung cancer therapy and its application in the clinic.